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Summary: Chinese sturgeon, Acipenser sinensis, is one of the endangered aquatic species and have been successfully bred and artificially produced in China. To analyze the role of aquaculture habitat conditions in growth of Chinese sturgeon, the growth performance, antioxidant capacity and immune responses of Chinese sturgeons under different tanks in the recirculating aquaculture system (RAS) were investigated. The fish (avg.wt. 2.83 ± 0.24 kg [SD]) were divided into two groups, one group were reared under three different water depths of tank (0.6, 1, 1.4 m) and the other group were under three different diameters of tank (2.5, 3.8, 7.5 m), which were named low‐depth (LD), medium‐depth (MD), high‐depth (HD), small‐diameter (SS), medium‐diameter (MS) and large‐diameter (LS), respectively. The results showed that at a depth of 0.6 m, the specific growth rate (SGR), weight gain rate (WG), serum glutathione peroxidase (GPX), alkaline phosphatase (AKP) and lysozyme (LZM) activities of Chinese sturgeons were significantly lower than those of other treatments (p <.05), while the food conversion ratio and malondialdehyde (MDA) showed a significant increased in this treatment (p <.05). In additional, when the fish in 2.5 m diameter tank treatment, the SGR, WG and the serum GPX, AKP, LZM indicator were significantly lower than the rest of the treatment (p <.05), while the serum MDA were significantly higher than the other treatment (p <.05). These results suggested that tank diameter and water depth had an influence on growth and therefore should be considered in RAS systems for Chinese sturgeon. [ABSTRACT FROM AUTHOR]

Summary: The growth, hematology, and immune responses of subadult Chinese sturgeon (Acipenser sinensis) (avg. wt. 25.11 ± 3.74 kg) were determined at three water temperature levels (12, 18, and 24°C) × three concentrations of total ammonia nitrogen (TAN) (0.05 ± 0.02, 1.03 ± 0.04, and 2.03 ± 0.05 mg/L) for 90 days in recirculating aquaculture system (RAS). At the end of the experiment, all fish were weighed and serum was collected for analysis using biochemical parameters. The temperature level had significant effects on the growth and hematology responses of subadult Chinese sturgeon under the RAS conditions. The specific growth rate (SGR) of subadult Chinese sturgeon was highest at 18°C compared to other temperatures; at this temperature, the total antioxidant capacity (T‐AOC), alanine aminotransferase (ALT) and lysozyme (LZM) activities were also the highest (p < 0.05). As the temperature rose, the oxygen consumption rate and ammonia excretion rates significantly increased (p < 0.05). In addition, there was no effect of TAN level on ammonia excretion rates of subadult Chinese sturgeon, while the oxygen consumption rate was greater in the high TAN group compared with the other groups (p < 0.05). The SGR of the fish was markedly reduced when the TAN level rose, and blood urea nitrogen (BUN), blood ammonia (BA), malondialdehyde (MDA) and cortisol in the serum were significantly elevated when the fish were in high TAN water for 90 days (p < 0.05), T‐AOC and LZM activities in the serum clearly decreased, indicating that the antioxidant system and nonspecific immune mechanism of subadult Chinese sturgeon appeared to be inhibited, which could raise the sensitivity of the Chinese sturgeon to various pathogens. The results of this study indicate that subadult Chinese sturgeon could achieve normal growth in the RAS, but that growth and hematology were significantly affected when the TAN concentration in the water was higher than 2 mg/L for an extended period. [ABSTRACT FROM AUTHOR]